Three‐dimensional Relativistic Magnetohydrodynamic Simulations of Magnetized Spine‐Sheath Relativistic Jets

Abstract

Numerical simulations of weakly magnetized and strongly magnetized relativistic jets embedded in a weakly magnetized and strongly magnetized stationary or weakly relativistic (v = c/2) sheath have been performed. A magnetic field parallel to the flow is used in these simulations performed by the new GRMHD numerical code RAISHIN used in its RMHD configuration. In the numerical simulations the Lorentz factor γ = 2.5 jet is precessed to break the initial equilibrium configuration. In the simulations sound speeds are c/ √ 3 in the weakly magnetized simulations and 0.3 c in the strongly magnetized simulations. The Alfvén wave speed is 0.07 c in the weakly magnetized simulations and 0.56 c in the strongly magnetized simulations. The results of the numerical simulations are compared to theoretical predictions from a normal mode analysis of the linearized relativistic magnetohydrodynamic (RMHD) equations capable of describing a uniform axially magnetized cylindrical relativistic jet embedded in a uniform axially magnetized relativistically moving sheath. The theoretical dispersion relation allows investigation of effects associated with maximum possible sound speeds, Alfvén wave speeds near light speed and relativistic sheath speeds. The prediction of increased stability of the weakly magnetized system resulting from c/2 sheath speeds and the stabilization of the strongly magnetized system resulting from c/2 sheath speeds is verified by the numerical simulation results.

Stability of three-dimensional relativistic jets: implications for jet collimation

“…Recently, Mizuno et al (2007) have extended this study to 3D relativistic magnetized jets, which may be stabilized (with respect to current-driven modes) by a sheath layer surrounding the jet core. A&A 519, A41 (2010) Focusing on the combination of linear and nonlinear studies, Perucho et al (2004a,b) studied the growth of single symmetric modes in relativistic jets, sweeping different parameters, such as jet temperature, Lorentz factor, and density ratio, with the external medium.…”

Radiation from accelerated particles in relativistic jets with shocks, shear-flow, and reconnection

“…In our simulation a relativistic jet plasma is surrounded by a sheath plasma [33,34]. This setup is similar to the setup of our RMHD simulations [22]. In our initial simulation the jet core has v core = 0.9978c (γ = 15) pointing in the positive x direction in the middle of the simulation box as in [2].…”

The Role of Macroscopic and Microscopic Jet Instabilities

“…Additional stabilization is provided by the presence of a significantly magnetized sheath or wind even if the jet core is super-Alfvénic [103,109]. The addition of a toroidal field component is not likely to alter this stability condition and we expect the Poynting-flux jet spine to be KH stable.…”